I am removing the intake manifold on my 91 Z/28. I used the same star wrench that worked on the other 11 bolts but for this one particular bolt, it stripped the insides. I can still get a decent amount of torque on it with an allen(sp?) wrench before it slips but it doesn't want to budge. I've sprayed it with WD40 and PB blaster over the course of the past 2 days and I've tried hitting it with a hammer to break it free with no luck. Anyone have any other suggestions before I take it to someone to have it drilled out?